Cerebrospinal fluid

Cerebrospinal fluid is a clear fluid that circulates through the brain’s ventricles and around the brain and spinal cord. It cushions the central nervous system and helps maintain its chemical environment and transport substances.

Choroid plexus: A network of specialized cells and blood vessels in the brain’s ventricles that produces most cerebrospinal fluid. It secretes most of the fluid that fills the ventricular system.
Meninges: The three membranes that surround the brain and spinal cord. The fluid occupies spaces defined by these protective membranes.
Lumbar puncture: A procedure that uses a needle in the lower back to collect cerebrospinal fluid or measure its pressure. It samples fluid from the spinal subarachnoid space for diagnosis.
Subarachnoid hemorrhage: Bleeding into the space between the arachnoid and pia mater, often from a ruptured aneurysm. Blood entering this fluid-filled space can be detected in cerebrospinal fluid.
Ventricular system: The connected cavities in the brain that contain cerebrospinal fluid. Fluid flows through these chambers before entering spaces around the brain and spinal cord.
Subarachnoid space: The space between the arachnoid and pia mater that contains cerebrospinal fluid. This is the main space where fluid surrounds the brain and spinal cord.
Hydrocephalus: An abnormal accumulation of cerebrospinal fluid within the brain’s ventricles. Blocked flow or impaired absorption can enlarge the ventricles and raise pressure.
Cryptococcal meningitis: A fungal infection of the meninges caused by Cryptococcus species, especially in people with weakened immunity. Cerebrospinal fluid testing is central to diagnosing this infection.
Arachnoid granulation: A projection of the arachnoid membrane into a dural venous sinus that permits cerebrospinal fluid absorption. These structures provide a major route for fluid to return to venous blood.
Cerebral aqueduct: A narrow channel connecting the third and fourth ventricles of the brain. Its narrow passage can obstruct flow between major fluid-filled chambers.

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